Gate controlled photocurrent generation mechanisms in high-gain In2Se3 phototransistors

• Main Authors: Island, Joshua O, Blanter, Sofya I, Buscema, Michele, van der Zant, Herre S. J, Castellanos-Gomez, Andres
• Format: Journal Article
• Language: English
• Published: 09-12-2015
• Subjects: Physics - Materials Science; Physics - Mesoscale and Nanoscale Physics
• DOI: 10.48550/arxiv.1512.02828

Nano Letters, 2015, 15 (12), pp 7853 - 7858 Photocurrent in photodetectors incorporating van der Waals materials is
typically produced by a combination of photocurrent generation mechanisms that
occur simultaneously during operation. Because of this, response times in these
devices often yield to slower, high gain processes which cannot be turned off.
Here we report on photodetectors incorporating the layered material In2Se3,
which allow complete modulation of a high gain, photogating mechanism in the ON
state in favor of fast photoconduction in the OFF state. While photoconduction
is largely gate independent, photocurrent from the photogating effect is
strongly modulated through application of a back gate voltage. By varying the
back gate, we demonstrate control over the dominant mechanism responsible for
photocurrent generation. Furthermore, due to the strong photogating effect,
these direct-band gap, multi-layer phototransistors produce ultra-high gains of
(9.8 +- 2.5) x 10^4 A/W and inferred detectivities of (3.3 +- 0.8) x 10^13
Jones, putting In2Se3 amongst the most sensitive 2D materials for
photodetection studied to date.